Streak Retinoscopy in Phakic, Aphakic, and Pseudophakic Dogs
World Small Animal Veterinary Association World Congress Proceedings, 2009
L.A.L. Mobricci1; J.J.T. Ranzani2; P.V.M. Steagall2; A.C.L. Rodrigues3; L.R. Carvalho4; C.V.S. Brandão2
1Faculdade de Medicina Veterinária, UNIP, São José dos Campos, SP, Brazil, Support by FAPESP; 2Faculdade de Medicina Veterinária e Zootecnia, UNESP, Botucatu, SP, Brazil; 3Faculdade de Medicina, UNESP, Botucatu, SP, Brazil; 4Instituto de Biociências, UNESP, Botucatu, SP, Brazil

Ocular refraction testing is recommended when screening animals for specific functions such as correcting ametropia in phakic, aphakic, and pseudo-phakic animals. There is great controversy in current veterinary medicine on the use of intraocular lenses to restore emmetropia after cataract removal. The objective of this study was to evaluate refraction error in dogs submitted to phakectomy by streak retinoscopy. Non-diabetic dogs of both sexes, with and without cataracts were subdivided into four groups: phakic, AD (aphakic), PD (pseudophakic with two piggyback human intraocular lenses) and LD (pseudophakic with one intraocular 41 D veterinary lens implant); phacoemulsification was chosen for surgical cataract removal. All groups underwent keratometry, ultrasonic echobiometry, and retinoscopy. Statistical analysis was by cross-sectional analysis, the Tukey, Students t, Wilcoxon, and Mann Whitney tests, and Pearson correlation; significance was set at 5%. Surgically induced astigmatism gotten by keratometry, was discrete and not statistically different between groups; mean corneal curvature was 40.46 ± 2.44 D in the different groups. There was no statistical difference between groups for eyeball axial distances by echobiometry except for axial length. There was statistical difference between groups for IOL dioptric power calculation by the SRK-T formula. Retinoscopy results showed no statistical differences in dioptric power in group PD at m0, and in groups AD and LD between m28 and m60, however there was statistical differences between groups at m60, with dioptric power of 18.50 D in Group AD, 5.25 D in group PD, and e 2.00 D in group LD. In conclusion, streak retinoscopy is an efficient method to evaluate ocular refraction in dogs, but is more difficult with ocular opacity; phakic dogs had less refraction error with discrete hypermetropia; aphakic dogs had strong hypermetropia; dogs with piggyback double lens implant calculated by the SRK-T formula had moderate hypermetropia; dogs with single 41 D lens implants had a similar refraction error to phakic animals; surgical astigmatism induced after clear corneal phacoemulsification is discrete.

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L.A.L. Mobricci
Faculdade de Medicina Veterinária – UNIP
São José dos Campos
SP, Brazil

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